Pollutants and cryptic species: investigating transgenerational effects on the performance and the microbiome of cryptic species.

Type:

Master Thesis subject (30 ECTS)

programme:

EMBC+

Anthropogenic activities have been altering natural environments for decades, where contamination by man-made pollutants poses a great risk for ecosystem health and biological diversity. Environmental risk-assessment methods have been developed and applied in order to prevent and/or mitigate human impacts, like single-species toxicity tests. Single-species are widely used as bio-indicators of pollution and environmental degradation, and data resulting from such assays are often used by regulatory agencies in the establishment of environmental regulations. However, the existence of cryptic species requires attention and care when interpreting data from single-species assessments. Cryptic species are morphologically indistinguishable, but show consistent genetic differences and may exhibit species-specific tolerances towards pollutants. This was already proven for cryptic species of the marine nematode Litoditis marina. Besides species-specific differences in resistance to pollution, resistance may also be transgenerational: some individuals may be more resistant toward pollutant than others and can pass this on to next generations. Pollutants may also influence the microbiome (bacteria associated with the gut) of different individuals/species. The microbiome (bacteria associated with the gut) of a species possibly plays an important role on organisms’ tolerance to different toxicants.
In this thesis we will subject species to pollutants and check their performance (population growth, behaviour, …). Moreover effects on the microbiome will be checked with Next Generation Sequencing to test if an effect on their microbiome can be found. Subsequently, we will collect the next generations of these species and raise them in treatments without pollution, to investigate if the species’ microbiome remains affected. Moreover, we will also subject them to pollutants, to see if they react differently than organisms from which previous generations have never been in contact with toxicants.